Chapter 780

This is a dream,

in his dream, Xu mang became the father of two children. The children were very smart, had good academic records since childhood, and were very filial. Every year, he got a scholarship and was soft handed. As a result, he fell in love with his youngest son Xu Yang in high school. He also found an airport less than 1.5 meters tall, and Xu mang was so angry that he vomited blood.

"Hello

"Professor Xie is calling for you."

"Wake up!"

Suddenly heard someone calling himself, Xu opened his confused eyes and saw a girl in front of him staring at him. He was in doubt. Did he communicate with her? Coco is to tell the truth... She looks average, worse than Xiaoman, not only sporadically.

"Ah?"

"Who are you?" Xu mang looked at her curiously, and his face was full of doubts and puzzles about the situation in front of him. However, he soon found that something was wrong. The atmosphere of the whole classroom seemed to fall into silence, and all the people around him looked at him.

What's the situation?

Why do you care so much about me all of a sudden? Is... Identity exposed? Glasses! Did you forget your glasses?

Xu mang quickly touched his black frame glasses without degrees. As a result, the glasses hung on his face, which was very strange. Although a pair of glasses can't change anything, it does change his temperament. His temperament changed... And so did people.

"This classmate!"

"Have you learned physics well?" Professor Xie asked solemnly, "well, to solve the problem I just mentioned, two identical charged particles with mass m and electric charge e start to be far apart. One particle is stationary, and the other moves towards the static particle with velocity V and aiming distance P equal to 2ke ^ 2mV ^ 2."

What is the scattering angle in the centroid system You asked, "Professor Xie."

Ah?

Particle system dynamics?

I didn't write about it.

Xu mang recalled that when he wrote the dynamics of the particle system, he did not write any problems about the dynamics of the particle system. It is estimated that this topic was compiled temporarily by himself, but it is really a very good problem. It involves the translational reference frame of scattered particles and the kinematic equation formula under the action of the horizontal inverse specific law force.

Of course,

this is just one of the solutions. In fact, there are many solutions to this problem, each of which is different, but the answer is the same.

"Oh..."

"I... did I go to the blackboard to write the process?" Xu asked curiously.

"Yes

"Come to the blackboard and write." Professor Xie said seriously: "by the way... If you can't write this question, I will give you a full mark if your process and answer make me satisfied."

Hiss!

Sleeping trough!

Play this big?

Hearing Professor Xie's words, many people at the scene took a breath of cold air and didn't be frightened. However, it was more a kind of nostalgia for Xu mang. He did not hesitate to test the legend of a physics college at the cost of failing to attend his own course. That is, he did not talk back to Professor Xie, and he was easy to eat and walk around.

Xu mang got up and walked through the crowd. Under the sight of seeing off the hero's expedition, he went all the way to the blackboard. He wrote down Professor Xie's questions in silence. Then he stood in front of the blackboard and looked at the topic in front of him. For a moment, he was a little stunned.

It seems that...

the blackboard is not enough!

"Cough!"

"Professor Xie?"

"What if the blackboard is not enough?" Xu mang asked cautiously, "these four big blackboards are not enough for me to write... What if this is broken in the middle?"

Professor Xie frowned, his eyes full of doubts, and seriously said: "impossible! This is my topic, not to mention four blackboards, two blackboards is enough, in short, you can write it... Can't write it down, tell me, today's class is not on, all depends on how you solve the problem. "

"..."

"Oh Xu mang nodded, helplessly picked up the chalk at hand and wrote down a word "Jie" with leather. He felt a little twisted. He quickly added a colon to make him comfortable...

I have to say,

I have to say,

I'm used to writing papers, and then go back to solve this common topic. I'm not used to it.

Originally,

everyone was not optimistic about Xu Mang, including Professor Xie. However, when Xu got a formula process according to the translational reference system of scattered particles, Professor Xie found that things were not as simple as he imagined.

Then, Professor Xie saw a very perfect calculation process of kinematic equation formula under the action of inverse square law force. He was not surprised. However, the expression of surprise remained short and soon returned to normal. The translational reference frame of scattering particles and the formula of kinematics equation under the action of inverse square law force could not explain any problems.The real difficulty lies in the back. We need to draw a plane two-dimensional diagram and calculate the following process according to the two-dimensional diagram.

Shua Shua Shua,

Xu mang is still working on the problem, but the speed is a little slow.

Wait!

Professor Xie saw that Xu mang wrote a group of relations. M1 and M2 are the masses of scattered particles and scattered particles respectively. When M1 = M2 = m, his expression gradually changed from apathy to a little panic. As expected, he saw a group of particles relationship conceived by Xu mang.

Let the velocities of particles 1 and 2 relative to the center of mass translational reference frame be v1c and V2C respectively, parallel and opposite, because M1 = M2 = m, v1c = V2C, VR = v1c - (- V2C) = v1c + V2C = 2v1c.

This...

this student... Is not easy!

Have you learned all the contents in advance?

At the same time,

at the same time,

the students were shocked. They didn't expect that the players who had been considered bronze Duan turned into the king's section, especially the two girls sitting in front of Xu mang.

"He..."

"that's amazing!"

"This guy is not pretending to be a pig eating a tiger, is he?" The girl who woke up Xu mang said to her best friend, "Peking University is just like a crouching tiger, a hidden dragon."

"I said... The more people who don't seem to care, the more likely they are to be peerless geniuses." The girl said with a smile, "do you still question my words? He must be a genius... From that decadent spirit, not a genius... God forbids. "

"Cut!"

"I retort!"

"Professor Xu of the university is not the kind of person you mentioned." "Professor Xu is a genius of genius, but at the same time he works very hard. I think... Genius and effort are always linked."

At this time,

at this time,

Xu Mang's problem-solving process was still going on, but he was about to arrive at the end. However, in a short period of ten minutes, Xu mang had conquered all the people present, including Professor Xie standing on the edge. He could not have imagined that there would be such a student.

Perfect!

Perfect!

is as like as two peas, but not a single symbol.

Professor Xie saw that Xu mang had successfully solved his problem, and he could not help saying, "good! In the middle of his speech, Xu mang went to the two movable blackboards on the edge and continued to write about the problem-solving process. However, his strange behavior made many people confused. He clearly solved the problem. Why is he still writing?

This...

what is this doing?

Professor Xie was just about to open his mouth to speak, but the next second, he held back.

Centroid translational reference frame?

This is...

the second solution?

Professor Xie was stunned for a moment. There was a second solution, and it was very convenient, but it was not suitable for freshmen. How could he?

No way!

At this time,

Professor Xie is more and more curious about this student. He stimulates himself again and again to refresh his understanding of freshmen. Is he really a freshman? Or was it a junior, a senior, or a graduate student?

Three minutes,

all the students present witnessed the birth of a miracle. Professor Xie's question seems to have two completely different solutions. The person who did this was actually a bronze player who had been sleeping in class before.

"Shit..."

"who is this guy? Why haven't I seen it? " "Have you ever seen him?" asked one of the students? Wearing such rustic glasses... There is no trace of young people's breath, and... How do I see his lazy look, how my heart is twisted. "

"Yes

"But they are better than us." On the edge of the boy sighed: "the pressure is so great... If I have the same talent as Professor Xu, that would be great."

"Ha ha!"

"You're thinking about Farting!" The boy disdained to sneer, and then continued to look at the blackboard, the second problem-solving process, looking at the problem, the boy suddenly felt that the figure of the student answering the question seemed to have been seen somewhere.

It's so familiar with your back...

how familiar it is!

"..."

"am I hallucinating?" The boy carefully said, "I... I think his back is a bit like Professor Xu!"

"You're bullshit."

"Before, you thought your girlfriend's back was like a female star. It was because of this relationship that you were together with others. I saw... Like a fart!" "Professor Xu is busy. How could he be so boring?" said the boy beside him? They do everything they can"It's true!"

A few minutes later,

Xu mang has completed the second problem-solving process, but the space left for him is only half of that of a blackboard.

What to do?

How to present the third way?

For a moment,

for a moment, Xu mang stood stupidly in his place, not knowing what to do.

At this time, Xu mang is in the mood, and finally has a feeling of youth, but this feeling is too short, not even half an hour.

"This classmate!"

"You are excellent!" Professor Xie showed his satisfied smile and said to Xu Mang: "you are much more than I expected. It's not easy to master these two methods at the same time. It's not too sloppy. There's no redundancy in the whole process. It's good, very good!"

Xu mang shrunk his neck and carefully said, "there is a third way to solve the problem... But I can't write it down."

......

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